Bacteria and fungi belong to the skin, but skin cells can die if bacteria and fungi penetrate cultured skin in the laboratory. Researchers have now found a way to apply cultured skin microbiomes to a relatively large surface area without destroying the skin.
A cheap and simple glass cylinder turned out to be the solution, researchers from Radboudumc in Nijmegen show in a study they recently published. in the scientific journal Microbiome.
The researchers placed a cylinder in the center of the cultured skin, a few millimeters from the edge of the skin in the culture container. The bacteria and fungi it introduced remained inside the cylinder, which was open at the top and bottom. They could not reach the edges of the cultured skin, where the skin barrier is ‘leaky’. This prevented micro-organisms from penetrating the skin from that edge, killing the skin cells under the stratum corneum and making the cultured skin unusable for research.
Lots of money
Bacteria and fungi protect the skin, but if the composition of the microbiome becomes out of balance, the skin can become sick. Conversely, conditions can also disrupt the balance of the microbiome. It is therefore important to investigate the interaction between micro-organisms and the skin in the lab. This allows scientists to learn more about conditions such as eczema and acne and to better test treatments.
The new Nijmegen method can also reduce animal research in the future, for example to test allergic reactions to cosmetics.
Normally, researchers are wary of microorganisms in the lab. Perhaps that is why it took so long for a PhD student to come up with this simple solution, says lead researcher in Dermatology Ellen van den Boogaard. “Everyone who works with cells and tissue in the laboratory is used to working in a super sterile manner, with antibiotics in the culture medium and alcohol spray to disinfect everything. When you use bacteria in the lab, there is also a risk of contamination for other experiments in the lab.”
Researchers do apply micro-organisms to the skin in a controlled manner. “But then we pipette a small drop in the middle of the skin so that it does not reach the edge,” says Van den Boogaard. “That small surface of approximately one millimeter means that you need a lot of material, a lot of tests, a lot of time and therefore a lot of money. If you have a cylinder with a diameter of six millimeters, you can do more analyzes on one piece of skin.” A major advantage is that no new expensive equipment is required. “Every lab has these cylinders.”
Dyke
Why wasn’t such a cylinder taken out of the closet earlier? Researchers often think too difficultly, says Van den Boogaard. “We were focused for a long time on closing and masking off the edges, and forgot that you can also build a dike.”
It was not as simple as it now seems, as if all you had to do was place a cylinder on the cultured skin. “When we started using the microbiome of patients instead of bacterial strains from the lab, we still got infections. We also had to adjust other conditions, such as temperature and humidity, to make the new method successful.”